Telephone-exchange system.



No. 855,546. PATENTED JUNE 4, 1907. H. G. WEBSTER. TELEPHONE EXCHANGE SYSTEM.

APELIUATION FILED DEC 16 1904 .rnn 'srnrns earn orrron HARRY e. wsss'rnn, or cnIcAco, ILLINO IS -ASSIGNOR TO MILO c. KELLOGG, or CHICAGQ, ILLINoIs.

TELEPHONE-EXCHANGE jsvsrEm.

citizen of the UnitedStates, and a resident of Chicago, countyof Look, and State of Illinois, ave inventedlcertain new and useful Improvements in Telephone-Exchange Sysmission and signaling is furnished from a cen' which the normal batteriy temsj, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawing, forming a part of this specification.

My vention' relates to telephone exchange systems in which current for transtral source located at the exchange; inwhich the spring jacks or connection-terminals are provided with but two contact pieces corre s'pondjng to the two line limbs, one contact piece being utilized as a test terminal; and in connections of the by the actuation of line are broken or altere .a cut-oil relay upon the insertion of a connecting plug into a spring jack. In systems 01'' this character, it has been common practies to leave one or both of the spring jack contacts normally disconnected from the line limbs, and by the action of-the cut-ofi relay to disconnect one or both line limbs from the calling battery and subsequently connect them with the wires leading to the springjack terminals. One result of thiscircuit arrangement is that when a subscriber is waiting for the operator to answer his call, the breaking of the normal line connection, whichlfollows' the insertion of the answering plug, causes an objectionable noise orclick to be heard through his receiver. r The object of my invention is to provide an improved orgtnii-aation of circuits and apparatus for systems of this class in which this objectionable click or noise is eliminated. Other advantages of my improved system will be apparent from the following description.

in accordance with-my invention, 1 provide spring jacks or switching terminals at the central exchange permanently connected with the line; and so arrange the circuits controlled by the cut-oll relaythat the circuit of the line limbs is not interrupted upon the insertion of an answering plug in response to a calling signal.

My invention will be further understood from the accompanying drawing in which Figure 1 illustrates diagrammatically two Specification'of Letters Patent. Application filed December 18, 1904. Serial No- 237,145.

Patented June 4,1907.

complete line circuits with appropriate cord connecting apparatus organized in accordme with a preferred form of my invention; andfin which Fig. 2- illustrates a modification oi the line circuit arrangement, with which the cord circuit of Fig. 1 is also adapted to co-o rate.

Referring to Fig. 1, the subscriber's apparatus shown at A is represented as consisting of a telephone hook switch It, signal bell b, condenser c, receiver-r and transmitter t;

the bell and condenser being in permanent.

bridge of the two line limbs, and circuit being closed'through the receiver and transmitter upon the elevation of the hook switch. Al-

though I have shown but one arran ement, it will be understood by those skille in the art that various other arr-an ements of the subscribers apparatus may e used, and I L e characters refer to corresponding parts in the two figures.

do not confine myself -to the particular ar- I rangement illustrated. Under normal conditions, the receiverhangs upon its book switch, maintaining its upper contact open, and the condenser c prevents a normal flow of current from battery (1 at the central office over the line limbs. When the subscriber removes his telephone from its hook, thus closing the up er contact of book switch it and establis 'ng a relatively low resistance path for the .fiowof current through the transmitter t and receiver 1, relay 4. at the central oflice .will be operated by the flow of current from said battery (3 through the winding of relay iflimbs l and 2 of the telephone line, arma time 6 and anvil 12 of relay 3, and thence to the oflice return or grounded side of the bat- I tery C. This flow of current through relay 4 causes its energiza-tion and the consequent I illumination of callin lamp 5; the circuit of lamp 5 .being comp et ed from battery C through anvil and armature of relay 4, anvil 13 and armature 17 of relay 3, to the-return I side of thebattery. Each subscribers line is provided with one or more spring jacks 9',

each having contact pieces 9 and 10 associated with limbs 1 and 2 of the line, respectively; contact piece 9 being directly connected with illumination of signal lamp 5 indicating to the operator that the subscriber has removed limb' l and contact piece 10 being connected "with limb 2 through the resistance The inakingaoalhshe inserts the answering plug? 1 flow from battery C through relay 2]. or 23 into a spring ack 9' corresponding 111g signal, thus causing contact piece lei of the plug to engage contact piece 9 of the spring contact piece 10 of the spring jack. Current will now flow from battery C through conductor 32, relay 2i, plug and jack contact Iii--10 to the junction point of resistance 8 and the winding of relay 3, atwhich point it will divide, a portion going through relay 3 to the return side of the battery C, and a portion going through resistance 8, armature 6 and anvil 12 to the return side of the battery; and resistance 8 is so proportioned with relation. to the resistance of the Winding of relay 3 that relay 3 will at this time receive sufiicient current to cause its actuation. The

' initial actuation of relay 3 interrupts a cir armaturefi and anvil 12 of relay 3.:

ever, a connect1n cuit of lamp 5 at armature 7 and anvil 13 and also interrupts the circuit previously traced through resistance 8 at armature 6 and anvil 12, and the further causes it to engage anvil 11, thus short circuiting resistance 8. After the disengagement of armature 6 With anvil 12, the current through relay 2]. will all llow through the winding ofrelay 3,while the current in the line limbs will flow through relay 3 as 'well, resistance 8 being included in this latter circuit until shortcircuited by the engagement of armature 6 with anvil 11. The closing of contact 149 of the. plug and spring jack has also completed a circuit of battery C through relay 20 to limb 1 of the line, thus increasing the current in the line limbs which was originally set up through relay 4, and causing the energization of relay 20 as long as the circuit of the limbs is completed through the receiver and transmitter. it will be seen at this time that, relay 21 being energized, the circuit of lamp 24 will be closed at the contacts of this relay, but the lamp will remain dark as long as its circuit is interrupted at the contacts of relay 20 through the energizationof the latter relay.

After being informed with what line corn 'nection is desired, in this case that of subscriber B, the operator tests in the usual rnannor by touching the tip of her calling plug 0 to the contact piece of-a jack associated with that line. It will be seen that under normal conditions, no noise will be heard in. the receiver of the operator's set S for the reason that the contact piece 14 of the calling plug is normally connected to earth or office return, and that contact piece 10 of the jack has adirect connection to the same earth or return which may be traced from the junction point of limb 2 with resistance 8, through of resistance 8 is interrupted through the energization ofrelay 3, and current will then to the call,- l

ed l thence through strand 1?, armature 26 of removement of armature 6 relay 22 and strand 1 7 similar 5 'eusly traced. through relay 20 and the consell, howi plug is in a spring jack of l the line tested, this'direct earth connection ment of Fig. Y Upon the insertion of a con'nfi f fill g Plug, 'cur- 1 9 associated with theaforesaid connecting plug,

, through contact %10 of the said plug and spring ack, contact p ece 10 ot the jack testack and contact piece 15 of the plug to engage contact piece 14 of the testing plug and lay 23, anvil 27 and winding 29 of the operators induction coil, thus producing the customary click which indicates that the line is busy. Upon the insertion of the and the actuation of the ringing key, relay 3 of the called line is er'iergized by current flowing from battery D through resistance 30, cont-act 15-i0 and thence through the Winding of relay 3 to the ground or oilice re turn. At the same time, the circuit of calling generator G is completed through strand 17,

contact 14-9, limbs 1 and 2 of the line and thence to the ethos return. Upon the restoration ol the ringing key, a circuit for relay 23 is completed similar to that previously traced for relay 21, and the consequent energization of relay 23 closes the circuit of lamp 25 cans ing its illumination and armature 26 disengages anvil 27, thus disconnecting the test winding 29 from the cord circuit, and engages anvil'28 thus completing the circuit of strand 1?. When the subscriber answers, a circuit of battery C is completed through to that previquent energization of this relay'interrupts at its contactsthe circuit of lainfip 25, causing its extinguishment. Strands l and 17, and

strands 18 and 19 of the cord circuit are intoo ductively united by the'condensers d and d I respectively, and the subscribers are now able to converse; current for the energiza. tion of their transmitters being furnished over the oi relay 4 in multiplewith limbs 31 and 12 of the line and the winding of relay 3. if either subscriber hangs up his re.- ceiver, the consequent deenergizatidn of rerelay or 22,

lay 20.01" 22 completes the circuit oi'the cor- I10 responding supervisory lamp 524 or and the illumination of both lamps constitutes the usual disconnect signal. 'It Will also be noted that after the disengagement of armature t3 and anvil 12, relay 3 will be energized 1 X5 to maintain the attracted position of its ar matures as long as circultis closed through. the substation receiver and transmitter, or

through contact I 0-i 5 of the plug and spring jack; and that it requires the interruption 220 of both of these circuits before the relay will become denergizedl I The line circuit arrangement of Fig. 2

differs from that of F ig. 1 in that-the resist ance 8 of Fig. l i replaced by the impedance 12 5 coil 31 inpcrnninent bridge of the linewith. thebattoryC and relay 4. its operation is substaru-ially the same as that of-the arrange- Y 1 and will be readilyunderstood.

plug 7 circuit which includes the winding rent from battery C will flow through relav 21 or 23, contact 15 10 of the plug and jacl: and the winding of relay 3, causing the energization of both relays. The actuation of relay 3 causes armature 6 to engage anvil 11, thus bringingrelay 3 into multiple circuit with impedance 31; the circuit of lamp 5 is controlled in the manner previously de scribed. The resistances 0 impedance 31 and relay 3 are so proportioned that after the engagement of armature 6 with anvil 11, relay 3 will still receive sufficient current to maintain the attracted position of. its armature as long as the plug remains in thespring jack, or circuit is closed through the substation receiver and transmitter. The circuit conditions in this figure for the supply of transmission current and during the process of testing and ringing will be readily understood from the description of the arrangement of Fig. 1. y

While separate batteries, C and D, have been indicated and so arate grounds or return connections fort ese batteries and the generator G, it Will be understood that these may be one and the same. It will be seen in oth arrangements indicated that after the removal of the receiver from the hook switch to initiate a call, there is no instant, as in systems of the, prior art, during which current ceases to flow through the substation apparatus, and it is this feature of m improved system, which results in the elimlnation of the objectionable click.

'It'will be understood b those skilled in.

the art that various modi cations of my invention may be made without departing from its spirit and I, therefore, do not limit myself to the precise structures shown and described. V p

Wherever the terms spring jacks or connectionteri'ninals are employed in the following claims, I desire it to be understood that they refer to such organizationsas a whole; rather than to their individual parts; but wherever in said claims a portion only of the spring jack is meant, such distinction is clearly pointed out.

l. The combination with a metallic tele-' phone; line, of a talking contact forming a part. at a connection terminal for the line, said contact being normally connected to earth, a central ource of current associated with the line an adapted to be included in the metallic circuit of the line when a connection exists to furnish current to the substation transmitters for talking urposes, means for establishing a direct cart connection intermediate of said contact and its associated line limb when theaiine is fnotjn use, means operated by current from said source to COD: nect said contact directly with the line when the line is in use and testing, apparatus to c'c-operate with said contact to indicate the limbs terminate,

said resistance condition scribed. 2. A tele of the line, substantially as phone system comprising a telephone line extending two limbs from ya 3 substation to the sleeve limbs'terminate, a cord circuit for making central office, tip and nection tosaid line, means .for holding con-,-

terminal contacts in which s d line versation over said line and cord circuit, a

source of current, means under the control rent,

completion of. said circuit, a controlling eleo tromagnet associated with said telephone line, a resistance, said resistance and-an-e1iQ-' ergizing winding of said magnet being connested serially with the sleeve: limb bf said telephone line andsaid source of current, a normal short circuit between the line limb and said source of current about said resist the control of said magnet, and means operated magnett'o remove said circuit said resistance nal beyond the control of the subscriber.

by sai 3; A telephone system comprising a tele phone line extending in' two imbs from a substation to the central ofiice, tip and sleeve terminal contacts in a cord circuit and connectmg plug for establishing connection through said terminal contacts to said line limbs,

means for holding conversation over said line and cord circuit, a source o'f current, means under the control of the subscriber for completing a calling circuit including said line tuated in response to the com short circuit, to shortwhich said line ance and energ1zing winding, means under the operator for energizm and'source of current,-a signal ac;-

pletion of said" QS I circuit, a resistance connected in circuit with f the sleeve limb of said line and 1ts terminal contact,a controlling electromagnet having an energizing winding connected in circuit between said terminal contact and said source of current, a normal short oircuiting path between said line limb and said source of current gizing the operator for net, and means operated-by said magnet to about said resistance and ener, winding, means under'the control of' energizmg said electromagremove said short circuit, to short circuit.

substation control, a source of current, a con-' nection terminal for said line having a test contact, a resistance, sa1d resistanceand an energizing winding of said electromagnet being connected in parallel circuit between said test contact and said source of current, conand to place said signal be yond the control of the subscriber.

4. A telephone system com rising a tele'- oflice, a line signal nor and to placesaid sigelectromagnet and for determining the idle or busy condition of the line through the agency of said test contact.

I 5 A telephone system coin ising a telephone line cxtending'in twolim sfroma substation to a central oflice, a line signal normally under the control of the subscriber, an clsctrornagnet for destroying said normal substation control, a source of current, a connection terminal for said line having a test contact, a resistance connected in circuit be tween said contact and a line limb, means operated by said electromagnet for establishing a connection between said contact and line limb about said resistance, and *means under the control of the operator for operating said electromagnet and for determining the idle or busy condition of the line through the agency of said test contact.

6. A,telcphone system comprising a tcles phone line extending in two limbs from a substation to a central ollicc, a line signal normally under the control of the si'ibscriber, an electromagnet for destroying said normal substation control, a source of current, a con i nection terminal for said line having a test contact, a resistance, said resistance and an energizing winding of said electromagnet be mal short circuit about said energizing wind- 5 mg, means. operated by said clectro'niagnct 5 for removing said short diicuit, and means under the control of the operator for operating said elcctromagnet and for dcterinining the idle or busy condition of the line through the agency of said test contact.

7. A telephone system comprising a telephone line extending in two limbs from a substation to acentral oiiicc, a line signal normally under the control of the subscriber, an

clectromagnet for destroying said normal substation control, a source of current, a con ncction terminal for said line having atest contact, a resistance connected. in circuit with said contact, a portion of said line limb and said source of current, a parallel branch including an energizing winding of said electromagnet and said source of current, means operated by said electromagnet for establish ing a connection between said contact and said line limb about said resistance and f or interrupting the normal line limb connection to said source of current. and means under the control of the operator for operating said electromagnet and for determining the idle or busycondition oi the line through the agencyof said test contact.

8. A telephone system comprising a. telephone line extending in two limbs from asubstation to a central oilice, a line signal normally underthe control of the subscriber, an clectromagnet for destroying said normal substation control, a source of current, a resistancc, said resistance and source of current being connected serially with an energizing winding oi said electroinagnet and one limb of said telephone line, a connection terminal for said telephone line having a test contact connected at a point between said resistance and saideloctromagnet winding, means operated by said clectromagnct for establishing a connection between said contact and line limb about said resistance, and means under the control of the operator for operating said electroniagnctfland for determining the idle or busy condition of the line through the agency of said test contact.

in witness whereof, I hereunto subscribe my name this 10th day of December, A. 1).,

' I HARRY G. WEBSTER.

Witnesses:

L. It). Kn iiiocc, G. E. illUELLER. 

